Prolongations of the Fundamental Structure (Initial Ascent and Arpeggiation)
Most of the prolongations of the first level middleground are concerned with delaying the completion of a fundamental descent. The initial ascent and arpeggiation involve a prolongation before the first note of the descent or primary tone. Instead of delaying resolution of the tension created by or it delays the introduction of that tension.

Earlier in his career, Schenker gave equal importance to ascending and descending linear progressions in the background, but he slowly came to realise that while all pieces eventually complete a descent not all of them begin with an ascent.

The initial ascent is the only ascending linear progression found in the first level middleground.

Like the initial ascent, the initial arpeggiation can be to either or . It can span a surprisingly long section of a work.